A cellular wireless communication system such as a Code Division Multiple Access (CDMA) 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) system, a Worldwide interoperability for Micro Wave Access (WiMAX) system, and the like, provides a variety of services to Mobile Stations (MSs). The drastic development of computer, electronics, and communication technologies is a driving force behind provisioning of diverse wireless communication services through a wireless communication network. The most basic wireless communication service is a wireless voice call service that enables MS users to conduct voice calls wirelessly irrespective of time and place. A wireless Internet service is also provided, which enables users to conduct data communication through the Internet over a wireless communication network at any place while they are moving.
Especially, Short Messaging Service (SMS) delivers text messages of a limited length between MSs irrespective of the communication state of a receiving MS, in other words, between MSs in idle modes. In general, the SMS limits a text message to about 80 bytes on a liquid crystal screen. Now, the use rate of the SMS is soaring, from personal usages to business usages. Beyond simple message exchanges between individual persons, the SMS has recently found its use in a wide range of group messaging, scheduled message transmission, e-mail reception notification, personal credit information management, financial information notification, and the like.
The growing use and importance of the SMS has increased the necessity of SMS security. Especially when a text message carries personal credit information or financial information, SMS security is very important. Accordingly, there exists a need for a specific technique for encrypting a short data burst transmitted by a terminal in order to protect SMS security.